Download BMT 242 Immunology

MLRS 242
Immunology
Pat Reed
Antibodies
Serum proteins
General antibody structure
Enzyme digestion fragments
Protein structure of
immunoglobulins
• Early amino acid sequence experiments were
unsuccessful—too much variation
• Multiple myeloma serum is 95% same antibody
• Bence-jones protein found in urine of myeloma
patients is excess light chain
• 110 amino acids highly variable, rest are quite
constant
• 5 different isotypes identified: based on type of
heavy chain: G,D,E,M,A
• Human light chains: 60% kappa (K) chains, 40%
lambda (L) chains
Ribbon model of antibody
Detailed structure of antibody
Ribbon model of variable region
• Variable region
contains highly
variable connecting
regions called
complementaritydetermining regions
or CDRs
• These regions are
also shown to be the
antigen binding sites
Model of antibody
Amino acid diversity of variable
domains – complementaritydetermining regions (CDRs)
Antigen – antibody interaction
Space filling model
Hiv protease and Fab fragment
Conformational change in Fab
domain
General structures of different
antibody classes
Subclasses of IgG
Secretory IgA
Receptor bound IgE
• Isotype – different
species
• Allotype – same
species, different
alleles
• Idiotype – same
species, different
VH and VL domains
Isotypic determinants – different
species variation within the
constant region
Allotypic determinants – different
constant regions within the same
species – different alleles
Idiotypic determinants – variations
in the variable region within the
same antibody type
B Cell Receptor - BCR
Fc receptors – bind Fc portion of
antibody molecules
Immunoglobulin superfamily of cell
receptors – evolved from common
ancestor gene
More members of the Ig
superfamily
Monoclonal antibodies
Many uses for monoclonal
antibodies
Antibodies can deliver drugs to
specific targets